An LED is a semiconductor light emitting device that converts electric current into light.
A wavelength of light emitted from such an LED varies depending on semiconductor material used for the LED. This is because the wavelength of emitted light varies depending on a band gap of the semiconductor materials, which represents difference in energy between valence band electrons and conduction band electrons.
Recently, the brightness of LED has been increased so that the LED is used as a light source for a display apparatus, an illumination device, and a light source for a vehicle. In addition, the LED can emit white light having superior efficiency by using fluorescent material or by combining LEDs having various colors.